This invention relates generally to groundwater and subsurface soil remediation.
There is a well recognized need for removal of subsurface contaminants that exist in aquifers and surrounding soils. Such contaminants can include various man-made volatile hydrocarbons including chlorinated hydrocarbons, e.g., volatile organic compounds such as chlorinated olefins including tetrachloroethylene, trichloroethylene, cis 1,2-dichloroethane and vinyl chloride. Other compounds include aromatic or polyaromatic ring compounds such as benzene, toluene, methylbenzene, xylenes, naphthalene, and propellents or explosives such as nitro anilines trinitrotoluene, and so forth. The groups of compounds are characterized by aromatic ring structures also include alkyl substituted aromatic hydrocarbons.
According to an aspect of the present invention, a method of treating a site includes sparging the site with an air/ozone gas stream delivered with a hydroperoxide, which is a substantial byproduct of a reaction of a contaminant present in the aquifer or soil formation with the ozone.
The air/ozone gas stream is delivered through a microporous diffuser that delivers the air/ozone gas in microbubbles. In some embodiments, the hydroperoxide is selected from the group consisting of formic peracid, hydroxymethyl hydroperoxide, 1-hydroxylethyl hydroperoxide, and chloroformic peracid or their derivatives. The hydroperoxide is selected based on the type of contaminant present in the site. The hydroperoxide is delivered as a surface layer over microfine bubbles including the air/ozone gas. Sparging introduces air including the oxidizing gas into the microporous diffuser. The microporous diffuser also introduces promoters or nutrients such as catalyst agents including iron containing compounds such as iron silicates or palladium containing compounds such as palladized carbon and platinum or platinum containing compounds.
According to an additional aspect of the invention, an apparatus for treating subsurface water includes a well having a casing with an inlet screen and outlet screen to promote recirculation of water into the casing and through surrounding ground area and at least one microporous diffuser disposed in the injection well that allows delivery of a pair of fluids with one of the fluids forming a coating over the other of the fluids. The apparatus also includes an ozone generator, an air compressor and compressor/pump control mechanism to deliver ozone (O3) from the ozone generator to the microporous diffuser, and a source of the liquid hydroperoxides selected from the group consisting of formic peracid, hydroxymethyl hydroperoxide, 1-hydroxylethyl hydroperoxide, and chloroformic peracid or their derivatives. The apparatus includes a pump to deliver the selected liquid hydroperoxide to the microporous diffuser.
One or more of the following advantages may be provided by one or more aspects of the invention.
The hydroperoxides promote decomposition of chlorinate olefins by forming a secondary liquid-phase reactive interface to the contaminants such as volatile chlorinate olefins and volatile hydrocarbons including chlorinated hydrocarbons, chlorinated olefins such as tetrachloroethylene, trichloroethylene, cis 1,2-dichloroethane and vinyl chloride and other compounds e.g., aromatic ring compounds, propellants, explosives, and so forth that are found as contaminants compounds as the contaminants enter the gaseous phase within the bubbles.
Promoters or nutrients are introduced with the hydroperoxides. The hydroperoxides are produced by reactions that decompose the contaminants. In the presence of the hydroperoxides, the promoters or nutrients can combine with the hydroperoxides and promote and accelerate the decomposition reactions. Further, when treating contaminants that have large number of double bonded carbon atoms or which are present in super-saturated conditions the addition of the hydroperoxides promotes rapid and efficient Criegee reactions of the contaminants.